Helping a Suzuki GS500

[elus1ve]

My friend has a Suzuki GS500 that she affectionately named Suki. She has been having trouble with it for the last 2 years and I want to give her a hand now that I have gained some exp from my Fz. I would much appreciate your help and advices.

Every so often she has been having trouble starting her bike. We always teasingly blamed it on the fact that she leaves the bike with the contact on (engine off, lights on) every so often when she stops to take a call or something similar. Usually 15mins at a time. Also thought her battery was old and needed replacing. Can't count how many times she needed a boost or had to recharge her battery.

However in the last few months it started getting worst. The engine died a few times when cruising at low rpm and it would automatically be followed by a difficult start. She went to the repair shop a few times to get her bike checked and the last visit she paid $400 for a battery change and some valve work that apparently was related to her trouble starting the bike. With the multiple visits and different repair shops, she did pay a fair amount to fix the issue.

The problem was not fixed though. I just came back from helping her as it died again. Had to push the thing to get it started and told her to it the rev up until she gets back home. It was actually funny as she was making a lot of noise while waiting at every lights and she was getting even more attention that usual, lol

In any case, the issue is definitely still there and I told her to bring the bike over. Try to stop wasting $ on repair shops for once.

I'm thinking the issue must be around the electrical system rather than the engine. This is what I am planning to check:
- The voltage when the engine is off - should be close to 12v.
- The voltage when the engine is idling - should go above 12v.
- The voltage when revving - should go above 13.5v.
- The alternator, but I don't know how to check that and during one of the visits to the repair shops, they told her the alternator is still good.
- Check the harnesses to see if there's any visual damage anywhere, in case there's a leak.
- Put some di-electric grease anywhere it might be useful. It's a naked bike and it sleeps outside everyday. If the electrical system is old, water is probably not helping.
- Replace any bulb I can with LEDs since I have accumulated a small stock of those. I figured saving a few watts can't hurt the poor thing.
- I might even put in a ballast and a hid bulb since I have a left over from my naked conversion. Her headlight seems really weak though, it might already be running a 35W bulb, in which case the hid wouldn't really be worth it in terms of saving watts.
- Would also check the spark plugs just in case, but I doubt it would be that. The engine seems to run ok.

So what do you think? Anything else I can check?

 

[Motogiro]

The possibilities are almost overwhelming! LOL. If the shop said she had a valve problem I would think they were talking about valve lash adjustment. Why did they come up with that idea? Poor compression? If the bike suffered poor compression and the shop adjusted the valves to help improve the compression they may have been too late. Before I would put money and labor into it, given the history, I would want to see what the compression was like. Then go from there.

 

[PhotoAl]

I would look at the voltage to the ignition and the computer for the fuel injection.

First though is the possibility of a dirty fuel system. Put some SeaFoam in it and see if that helps. Potential problems/stuff to check:

Dirty Injectors
Spark Plugs - old worn, wrong type
Fuel Filter - dirty/cloged
Fuel Pump - delivering enough pressure
Fuel Pressure Regulator - would cause fuel pressure problems

Assumed that it is fuel injected. If not it has a carburetor it could be a dirty low speed circuit, choke problems etc. Again fix is Sea Foam.

Hope these help.

 

[elus1ve]

Yea there's a lot of possibilities :/

Well the repair shops tried a few things but she could only remember what they told her on her last visit, and vaguely at that. That's the valve adjustment she mentioned. I do not know the history of everything they did but there was no replacement of major parts.

You are mentioning compression. If the compression was at fault, wouldn't the engine run poorly? It does run ok when it starts (other than the few times it died while cruising at low rpm). There is no power lost while revving and why would the battery be dead every so often if there was a compression issue? As everytime Suki doesn't want to start, a battery charge puts it back to normal / or a boost, push coupled with enough riding time to charge it back.

If there is a problem with the engine, then I won't be of much help but can it really be an engine issue?

 

[elus1ve]

I would look at the voltage to the ignition and the computer for the fuel injection.

First though is the possibility of a dirty fuel system. Put some SeaFoam in it and see if that helps. Potential problems/stuff to check:

Dirty Injectors
Spark Plugs - old worn, wrong type
Fuel Filter - dirty/cloged
Fuel Pump - delivering enough pressure
Fuel Pressure Regulator - would cause fuel pressure problems

Assumed that it is fuel injected. If not it has a carburetor it could be a dirty low speed circuit, choke problems etc. Again fix is Sea Foam.

Hope these help.

Thanks, will do a check of all of these and try the seafoam. Will have to google on how to check pump. That model is not fuel injected, so don't think I will find a computer in there.

 

[Dresnewtoy]

While you're at it check the rectifier/voltage regulator. Had a gs500f before i got the FZ and those can be problematic too.

 

[tom.gabriele]

I actually just bought an FZ last night for me to ride while I am doing some work on my GS500. And by "some work" I mean " a lot of work":

I am no expert, but I am learning as I go.

From the sounds of it, I think there's a good chance that it's the battery. I had a Virago 250 before either of these bikes, and left it on several times. One battery was left on, drained completely, recharged, and had enough juice to start the bike but was just a huge drain on the electrical system, so it felt like the alternator only had enough power to charge the battery, and it wasn't able to get enough spark. It would bog down at higher RPM (when it needs to be providing sparks at greater frequency) and also had problems at idle (not as much electrical generation).

Try starting the bike, then disconnecting the battery. It should still run (assuming the alternator is working), but if it runs better, you know the battery is causing the trouble.

 

[jdoorn14]

I'd also suggest heading over to GSTwins.com to ask the gurus over there, if you haven't already. Just like folks here know the fz inside & out, people there have done full tear-downs and rebuilds on bikes & engines.

Another thing you might check would be to ensure there are no kinks in the gas lines from tank pet**** to carburetor. Even a slight kink might cause hesitation/dying at speed, even if it's fine going slower. The other question would be to find out what happens if she switches the fuel pet**** to prime and rides that way. This only removes the vacuum fuel valve from the equation. If it's fine in prime, I'd suspect a vacuum leak.

 

[tom.gabriele]

Another thing that comes to mind from your description is fuel starvation. A common cause of this is a poor fuel pet**** design on the GS. See this thread over at GS Twins: Fuel starvation - A simple petcock fix

The community surrounding the GS over on GS Twins is impressively knowledgeable, helpful and friendly. Especially adidasguy.

If you register over there, you are sure to get your answer.

PM me over there if you end up starting something over there. Same username.

 

[elus1ve]

Thanks guys.I think I will do a first round of checks on the GS before bringing it to the GS Twin forum. I think the issue will probably take a while to find given the various possibilities and the fact that the repair shops also were unable to pinpoint the issue right away. I initially thought it was only electrical. It will probably take some trial and error. Once I have eliminated some of the variables, I am going to post on the GS forum so that the GS gurus can really dig into something.

I will start by checking the electrical components then move to the fuel system. That will also give me some direct input on the bike itself, so I should have more useful info on the symptoms.

Oh and tom.gab, :welcome: to the FZ6 forum! You are indeed doing 'some' work on your GS Looks fun.

 

[Motogiro]

Yea there's a lot of possibilities :/

Well the repair shops tried a few things but she could only remember what they told her on her last visit, and vaguely at that. That's the valve adjustment she mentioned. I do not know the history of everything they did but there was no replacement of major parts.

You are mentioning compression. If the compression was at fault, wouldn't the engine run poorly? It does run ok when it starts (other than the few times it died while cruising at low rpm). There is no power lost while revving and why would the battery be dead every so often if there was a compression issue? As everytime Suki doesn't want to start, a battery charge puts it back to normal / or a boost, push coupled with enough riding time to charge it back.

If there is a problem with the engine, then I won't be of much help but can it really be an engine issue?

An engine can have an issue if the jets in a carb are dirty or worn.

Not knowing why the battery is going dead reminds me to think of how often does the engine quit and how many times is it restarted which may flatten an optimal battery. Not knowing the complete history, I think the battery load test and voltage tests have been done as well as a current leak test. These you have touched on in your first post although you may not have done them yet.

Engines with less than optimal compression can take more cranking to get started and as they warm up the compression increases and the engine runs much better. Yes poor compression can mean a dead battery.

You mentioned checking plugs. While you're there do a compression test.

Could it be riding habits? Short runs with the bike or lots of stop n go?

If it's just a cranking issue then It could be electrical and do test the R/R and stator as well as load test the battery as previously mentioned.

 

[jb1390]

I'm with Tom that it is simply the battery. Also, check the ground cable where it attaches to the motor-that cable will be mounted to "clean" aluminum, which could oxidize underneath the connector. If that happens, it will sort of make a connection, but won't allow all the current that it should. This will affect starting, and charging as well.

A good lead acid battery should read 12.6 (approx) volts with no load. You can turn the lights on and see what happens-an even better way to check the voltage is main positive on the battery to a clean ground on the engine-that way you can see if there is any voltage drop due to poor connections.

Your voltage with the engine running at idle may be below 12.6-I'm not sure that the alternator puts out enough energy at idle to run the headlight and other electronics without a slight drain on the battery. On a car, it almost certainly would, but on a motorcycle the alternators are much smaller, so disconnecting the battery at idle might cause the engine to stall out very quickly.

I would check your voltages and post back-

1. open circuit voltage (key off)
2. loaded battery voltage (key on, engine off)
3. voltage while cranking motor
4. voltage at idle
5. voltage when revved above 4-5k rpms

 

[tyler2011]

I'd suspect the battery is at fault first. Replaced mine this season as it would loose charge after a week and not start the bike. If I charged it it would be fine for a few days and as long as I rode regularly. Auto parts stores can test the battery to see if a cell is bad. I also noticed that if I left the headlight on for even a few minutes the battery would be weak on start. No problems since I replaced it.